1. Field of the Invention
This invention relates to block units for a block toy.
2. Related Art
A block toy is well known which is formed by combining block units having protrusions and recesses. There are available a variety of block units different in configuration for block toys; however, the standard structure of a block unit is as shown in FIG. 10(a). That is, the body of the block unit (hereinafter referred to as "a block body", when applicable) is in the form of a rectangular box made up of two end walls, two side walls, and a top wall, being opened in one direction. The block body has eight protrusions 3a through 3h on the outer surface of the top wall at equal intervals. Furthermore, FIG. 10(c), it has three annular protrusions 4a, 4b and 4c (hereinafter referred to as "tubes 4a, 4b and 4c", when applicable) extended from the inner surface of the top wall, which is opposite to the outer surface of the wall on which the eight protrusions are formed, to the plane defined by the outer edges of the two end walls and two side walls of the block body. The two end walls and two side walls of the block unit and the tubes 4a, 4b and 4c define a recess a. The block unit shown in FIG. 10(c) is relatively small in thickness. The block unit shown in FIG. 10(a) is standard in thickness, and its tubes have a length in proportion to the thickness.
The block units shown in FIG. 10(a) and (b) are joined into one unit as follows. That is, the block unit shown in FIG. 10(a) or (b) is turned over and set on the block unit shown in FIG. 10(a) or (b). Under this condition, those block units are pushed against each other, as a result of which three spaces A, B and C defined on the top wall by the eight protrusions (each space being defined by four adjacent protrusions) are engaged with the three tubes 4a, 4b and 4c, respectively, so that the two block units are connected to each other. In this operation, the protrusions of the block unit of FIG. 10(c) are engaged with the recess a which is defined by the four side walls and the three tubes. The two block units may be connected to each other in various manners. For instance, the two block units are set in the same direction, and one of the tubes of one of the block units is engaged with one of the above-described spaces on the top wall of the other block unit, or two tubes are engaged with two spaces.
On the other hand, a moving block toy is available in which a drive source, namely, an electric motor is built in a block unit (hereinafter referred to as "a motor block unit", when applicable). The motor block unit is several times as large in size as the standard block unit. The motor is built in the block unit in such a manner that the rotary shaft of the motor is arranged perpendicular to the direction of engagement (or disengagement) of the block unit, and its both end portions are protruded from the block unit. Rotating members such as tires, gears, belts and pulleys are mounted on the two end portions of the rotary shaft. With moving block toys, a variety of structures can be formed which are movable. The moving block toys are objects in which children full of curiosity are interested.
The conventional motor block unit, having its rotary shaft sticking out of the block body, suffers from the following difficulties: If, with the motor block unit coupled to a battery block unit, the switch is turned on, then the motor's rotary shaft sticking out of the block body is rotated, thus being hazardous. If the rotary shaft sticking out of the block body is bent by external force, then it becomes impossible to accurately transmit the torque to the rotating member such as a tire. Since the end portions of the rotary shaft are protruded from the block body, the motor block unit is a special block unit; that is, it cannot be employed as a standard block unit, not being applicable to different moving block toys. Furthermore, since the direction of the rotary shaft is perpendicular to the direction of engagement of the block unit, the direction of utilization of the torque provided by the motor is limited; that is, use of the motor block unit is limited.